The present invention relates to a magnet lead for connecting a power supply to a superconducting magnet coil.
A superconducting magnet typically comprises a coil of relatively fine superconducting wire. To enable the superconducting wire to function as a superconductor, the coil must be maintained at an extremely low temperature below the transition point of the superconductive material. It is well known to locate a superconducting magnet coil in a bath of liquid helium within a container to maintain it at an acceptable operating temperature.
The magnet coil is typically connected to a power supply by a pair of leads. The power supply is typically at room temperature, and accordingly heat is typically conducted to the magnet coil through the leads. Also, heat generated in the leads due to ohmic losses is typically transferred to the coil.
It has been proposed to employ a lead comprising a normal portion near the power supply and a superconducting portion near the magnet, spliced end to end. However, joining the normal conductor to the superconductor complicates assembly of the lead. Also, during operation the normal portion must be cooled to an extremely low temperature so as to prevent it from transferring heat to the superconducting portion and raising the temperature thereof beyond its superconducting range. It is difficult to provide such cooling efficiently.